Advertising-supported distribution of audio-video data may be implemented from a content server to remote client devices over computer networks, telecommunications networks, and combinations of such networks, using various methods, for example progressive downloading or streaming. Platforms for such distribution may include sites that offer a great variety of different programming, including both newly released episodes of serial programs, major features, documentaries, special events, archives of past episodes and classic serial programs, of different types targeted to users having various different demographic profiles. One or more video ads may be inserted into each video program and sold to advertisers who are charged based on how many times each advertisement is played on a client device; i.e., for each video ad impression.
Prospectively, it may be desirable to provide estimates to advertisers concerning how many ad impressions are available for purchase in a particular future time period for a defined advertising target. Such information, sometimes referred to as “ad inventory” may be useful for planning advertising costs/revenues and generally facilitating commerce. However, because of the complexities of sophisticated video content platforms, prior methods of estimating ad inventory in a streaming video system may be subject to certain shortcomings. For example, prior methods may be inaccurate, inefficient, or both, for estimating a number of unique viewers that will be exposed to one or more ads in a particular ad campaign. Consequently, management of ad inventory based on prior estimation methods may be prone to problems such as unanticipated surpluses or shortages of ad inventory, or high uncertainty regarding the number of different people a particular ad campaign will reach. These and other limitations of prior methods for estimating and managing ad inventory in a streaming video system may be overcome by the novel methods and apparatus disclosed herein.